1. Field of the Invention
The present invention relates to a copying apparatus employing a roll of copy paper.
2. Description of the Prior Art
In a prior art copying apparatus employing a roll of copy paper, the copy paper is cut so as to have a desired length by a copy paper cutting device when the original document or optical device reaches pre-determined position, and the last copy paper sheet having a length shorter than the distance between transport rollers situated in a copy paper transport pass is often left. This last copy paper sheet causes jamming in the copy paper passageway.
It is an object of this invention to solve the problem mentioned above and to provide a copying apparatus preventing the last copy paper sheet from a roll of copy paper from jamming.
A typical prior art comprises on the way of an original document passageway (a) detecting means for commencing feeding of the first sheet of the roll-like copy paper synchronous with detection of the lending edge of the original document and for severing the roll-like copy paper to stop feeding on the occurence of the detection of the trailing edge of the original document, (b) detecting means for detecting the trailing edge of the original document after the copying exposure operation to return the original document in a direction opposite to the copying exposure direction, (c) a cam for beginning to feed a second and further cppy paper during the time period when the original document is returned in the direction opposite to the copying exposure direction, and (d) detecting means for detecting the leading edge (i.e. the trailing edge in the reverse direction) of the original document returning in the reverse direction opposite to the copying exposure direction to transport the original document again in the copying exposure direction. In this prior art approach, three detecting means and a cam cooperate with each other to feed the second and further copy papers synchronously while the original document is returned in a direction opposite to the copying exposure direction so as to shorter the time for copying. The returning speed of the original document is chosen to be relatively greater to shorten the time for copying further. Therefore when the original document returns in a direction opposite to the copying exposure direction, the leading edge of the original document does not coincide with the leading edge of the copy paper because the transport distances in a direction opposite to the copying exposure direction are different, depending on the inertia force of each original document.
It is an object of this invention to provide an electrostatic copying apparatus for accomplishing a plurality of copies in a condition where the leading edge of the original document coincides precisely with the leading edge of the copy paper.
It is an object of the invention to provide a copying apparatus capable of mounting selectively an original document manual feeding assembly or an original document automatic feeding assembly, on the top of the frame of the apparatus.
Another object of the invention to simplify the construction of the original document manual feeding assembly and the original document automatic feeding assembly.
In another prior art arrangement of an electrostatic copying apparatus employing an original document automatic feeding assembly for feeding automatically a plurality of original documents into an original document passageway, there are provided an upper transport roller and a lower separate roller spaced from each other along axial lines thereof in a comb fashion upstream of a slanting original document plate along the transport direction, the lower separate roller being driven in a direction reverse to the transport direction to advance a top sheet of original documents sliding down on the original document plate by their own weight, thus to prevent a plurality of the original documents from being fed. In accordance with this prior art arrangement, the original document is modified or the leading edge of the original document is folded because the distance between the axes of the two rollers is less than the radii of the rollers.
Accordingly it is an object of the invention to provide an original document automatic feeding assembly capable of feeding original documents one by one positively to prevent original documents from being modified.